Lipids are called the three major nutrients necessarily required in a biological body, together with proteins and carbohydrates, and their main role is known as the energy storage and in vivo various cell membrane components. In addition, hundreds of hormones present in the biological body also fall in a field of lipids, and it is known that the lipid plays a very important role as a signaling material, such as activation of genes in response to a variety of lipids in nuclear receptors of cells being the basic structural units of the body.
Since lipids have mostly complex lipid characteristics due to amphoteric properties and it takes a long time in the case of the liquid-liquid extraction method, the demand for new technique which can simply extract only lipids from the biological sample is continuously growing.
The Folch method is widely used in the biological and biochemical field to date as a first way in 1956 which can extract lipids from a biological sample using the organic solvents of methanol and chloroform and distilled water. This method is based on the liquid-liquid extraction method, and has been used while changing some of kinds and composition in the organic solvents so as to be suitable to the kind of lipids to be analyzed.
The inventors attempted to develop a simple extraction method by applying to the lipid extraction the QuEChERS method widely used in food analysis and environmental analysis fields. This extraction method succeeded in significantly reducing the extraction time to about 10 minutes, while having also excellent extraction efficiency, compared to the widely used liquid-liquid extraction method. However, this method has a disadvantage that it cannot be connected online to the chromatography-mass spectrometer due to non-resuable magnesium sulfate for absorbing moisture, and the process of absorbing moisture is an exothermic process, so that the risk that can result in modification of the lipid exists.
Upon reviewing patent references, it can be seen that most references are based on the liquid-liquid extraction method and take the expanded form (U.S. Pat. No. 8,383,845 B2; U.S. Pat. No. 8,273,248 B1; U.S. Pat. No. 8,211,308 B2).